The hot water heater is one of the better inventions of mankind. Before they were created people had to dump cold water in a pot and then boil it. Nowadays you just turn on your tap, wait a bit for the cold water to be pushed through the pipes, and you have hot water on demand.
As this Wikipedia entry details, there are a few energy sources for heating water. Natural gas and electricity are most common but some homes also use either fuel oil or propane. There are now also new ways of heating water such as using a heat pump or solar heat. The newest way to heat water is using solar energy. Solar energy is both clean and renewable. The only real cost is having the panels installed, something that has come down dramatically in price in recent years.
Natural gas is a popular way to heat the water because these water heaters can be installed pretty inexpensively using a local HVAC company that provides water heater services. Natural gas is relatively inexpensive so they are also less expensive to maintain than any other conventional way of powering a water heater. The emissions from burning natural gas are vented outside of the home which also brings in fresh air to continue the combustion process.
Electric water heaters are also common. They are more expensive to operate than natural gas water heaters but are still reliable and work particularly well in areas that have smart electrical power distribution systems in place. The system can turn these off when the load is high and heat the water during times when the load is lower such as in the middle of the day or at night.
When it comes to water heater service Alexandria VA people there have many options. There are a number of good quality local HVAC contractors who can install and service water heaters regardless of what fuel they use. Most of these outfits can send out a technician during an emergency such as when a water heater bursts. These contractors also offer other services such as installing and maintaining heating and cooling systems.
One of the newest types of water heating systems is the tankless water heater, as detailed here. Having been around for a bit most HVAC contractors have plenty of experience installing these systems in homes. These are known by other terms such as on-demand, instantaneous, and instant-on water heaters.
A tankless water heater, as its name implies, has no water kept internally within it outside of what passes through the heat exchanger coil. These types of water heaters usually use copper because it is has a high thermal conductivity. These can either be installed in a central location in the home or the house can have multiple tankless water heaters in it, each right by a faucet. These system are more expensive to install than conventional water heaters but they are very convenient as when you turn on the water it is instantly hot.